Commit 8d50cdf8 authored by Pawan Gupta's avatar Pawan Gupta Committed by Borislav Petkov
Browse files

x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data 



Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent 99a83db5

Documentation/ABI/testing/sysfs-devices-system-cpu

+1 −0
Original line number Diff line number Diff line
@@ -526,6 +526,7 @@ What: /sys/devices/system/cpu/vulnerabilities 
		/sys/devices/system/cpu/vulnerabilities/srbds

		/sys/devices/system/cpu/vulnerabilities/tsx_async_abort

		/sys/devices/system/cpu/vulnerabilities/itlb_multihit

		/sys/devices/system/cpu/vulnerabilities/mmio_stale_data

Date:		January 2018

Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>

Description:	Information about CPU vulnerabilities

arch/x86/kernel/cpu/bugs.c

+22 −0
Original line number Diff line number Diff line
@@ -1902,6 +1902,20 @@ static ssize_t tsx_async_abort_show_state(char *buf) 
		       sched_smt_active() ? "vulnerable" : "disabled");

}



static ssize_t mmio_stale_data_show_state(char *buf)

{

	if (mmio_mitigation == MMIO_MITIGATION_OFF)

		return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);



	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {

		return sysfs_emit(buf, "%s; SMT Host state unknown\n",

				  mmio_strings[mmio_mitigation]);

	}



	return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation],

			  sched_smt_active() ? "vulnerable" : "disabled");

}



static char *stibp_state(void)

{

	if (spectre_v2_in_eibrs_mode(spectre_v2_enabled))
@@ -2002,6 +2016,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr 
	case X86_BUG_SRBDS:

		return srbds_show_state(buf);



	case X86_BUG_MMIO_STALE_DATA:

		return mmio_stale_data_show_state(buf);



	default:

		break;

	}
@@ -2053,4 +2070,9 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char * 
{

	return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);

}



ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf)

{

	return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);

}

#endif

drivers/base/cpu.c

+8 −0
Original line number Diff line number Diff line
@@ -564,6 +564,12 @@ ssize_t __weak cpu_show_srbds(struct device *dev, 
	return sysfs_emit(buf, "Not affected\n");

}



ssize_t __weak cpu_show_mmio_stale_data(struct device *dev,

					struct device_attribute *attr, char *buf)

{

	return sysfs_emit(buf, "Not affected\n");

}



static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);

static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);

static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
@@ -573,6 +579,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL); 
static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);

static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);

static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);

static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);



static struct attribute *cpu_root_vulnerabilities_attrs[] = {

	&dev_attr_meltdown.attr,
@@ -584,6 +591,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { 
	&dev_attr_tsx_async_abort.attr,

	&dev_attr_itlb_multihit.attr,

	&dev_attr_srbds.attr,

	&dev_attr_mmio_stale_data.attr,

	NULL

};

include/linux/cpu.h

+3 −0
Original line number Diff line number Diff line
@@ -65,6 +65,9 @@ extern ssize_t cpu_show_tsx_async_abort(struct device *dev, 
extern ssize_t cpu_show_itlb_multihit(struct device *dev,

				      struct device_attribute *attr, char *buf);

extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);

extern ssize_t cpu_show_mmio_stale_data(struct device *dev,

					struct device_attribute *attr,

					char *buf);



extern __printf(4, 5)

struct device *cpu_device_create(struct device *parent, void *drvdata,